The detection of changes in the circulation and surface topography of the optic nervehead and adjacent structures is crucial for the early diagnosis of glaucoma. A new technique, called laser contour angiography, has recently been invented (by Shapiro) to quantitate these changes and has been used to obtain high precision topographic data in normal human subjects. Because only a small proportion of ocular hypertensive patients go on to develop visual field loss, a longitudinal study of glaucoma in human subjects would have to involve a large patient population and would require many years of observation. The recent availability of an animal model of chronic glaucoma makes it possible to study these relationships over a short time span and under well controlled conditions. The experimental glaucoma model is difficult to use. In the coming year we will use both laser obstruction of the aqueous outflow pathway and pharmacologic alteration of aqueous humor production to more closely regulate intraocular pressure, to more closely model chronic glaucoma, and to overcome the problem of hazy media during the early stages of experimental glaucoma. The eyes of the anesthetized monkey move about during the angiogram so that the field of interest often goes outside the field of view of the fundus camera. An eye movement compensation device has been designed to overcome this problem, and will be further developed in the coming year. In order to compensate for eye motion, the eye's position must be measured. A measurement system suitable for glaucomatous eyes will be constructed in the coming year. We plan to continue the longitudinal study of optic disc topography and circulation in the glaucomatous eye, and also in the eyes of monkeys with experimental systemic hypertension. Our pilot experiments this year with the latter model indicate that monkeys with a coarcted aorta have the same retinal circulation as normal monkeys. These experiments are an important preliminary to a study of the combined effects of glaucoma and systemic hypertension, and will be continued.